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Topic: 314.29 pull box questions

User: aisid, Location: NJ

Asked on: Monday, April 28, 2025 at 10:57 pm EDT
Answered on: Tuesday, April 29, 2025 at 12:04 am EDT

Question: First time DIYer installing a Tesla wall connector in the driveway using 3/4" PVC in 18" deep trench. I didn't want to come up through the concrete base of the 4x4 and our ca1800 home has a rock foundation so I used two 45s at both locations. Unfortunately this put me over the 360° bend limit and the inspector failed the setup. I should be able to install a 2-gang pull box another 4x4 near the halfway point and come up with two 90° bends, right? At this point would I pull the conductors through and then bend back down 180° or should I splice them together somehow? 3x6# SW Simpull. My electrician was charging 3x markup on 6/3 Romex and making a big deal out of providing materials at cost, so I figured I should be able to figure this out myself. Thanks!

Okay, you're on the right track, but let's refine the plan and address the specifics. Here's how to handle the situation, along with some crucial code considerations

Understanding the Issue:
360-Degree Rule

The National Electrical Code (NEC) limits the total bend in a conduit run between pull points (junction boxes, handholes, etc.) to 360 degrees. This is to prevent excessive friction that can damage conductors during pulling and make future maintenance difficult. Your two sets of 45-degree bends at each end exceeded this limit.


Conductor Size and Conduit Fill

6 AWG is a relatively large conductor. Ensure your 3/4" PVC conduit is adequately sized, especially with multiple conductors.

Proposed Solution with a Pull Box


Location and Placement

Yes, adding a 2-gang (or even a single-gang, depending on space) pull box near the halfway point is the correct approach. Choose a location that is easily accessible for future maintenance. Make sure it's not in a spot where it's likely to be run over or easily damaged. The new 4x4 should be securely mounted and provide a stable base for the pull box.2.

Conduit Bends

At the pull box location, use two 90-degree sweeps to bring the conduit up into the box. Avoid using standard 90-degree elbows as sweeps have a larger radius and make pulling easier. Ensure the radius of the 90-degree bends is compliant with the NEC for 6 AWG conductors.3.

Wiring Options and Splices



THIS IS CRITICAL



PREFERRED: Continuous Run (No Splices)

The best and most reliable method is to avoid splices in the pull box if possible. If there is enough slack in the conduit, pull through all conductors using a lubricant rated for electrical use to minimize friction. Then, bend back down and continue the run. This minimizes potential points of failure.

If You MUST Splice (NOT IDEAL, BUT SOMETIMES NECESSARY)

If you absolutely cannot make a continuous run (e.g., the existing wires are too short), then
only use approved splicing methods inside the pull box. Do not use wire nuts alone. Use one of the following, and make sure to torque connections to the manufacturers specifications:

Polaris Connectors

These are insulated, lay-in connectors that are easy to use and provide a very secure connection. They are more expensive than other options, but offer a high-quality, reliable splice.

Mechanical Set-Screw Connectors

Use UL-listed mechanical set-screw connectors specifically rated for splicing copper conductors. These often come pre-insulated.


Crimped Splices

Use appropriately sized crimp connectors (e.g., insulated butt splices) and a proper crimping tool. After crimping, insulate the connection with multiple layers of high-quality electrical tape or heat shrink tubing.

Important Splicing Considerations



Accessibility

Splices MUST be accessible. That's why they need to be inside the pull box.

Fill

The pull box must be large enough to accommodate the splices and any required wire bending space (see NEC for box fill calculations). A 2-gang box may be too small, depending on the size of the splices.


Torque

Torque connections properly. Under-torqued connections are a leading cause of electrical fires.4.

Bending the Wire

Bending 6 AWG wire can be challenging, especially in tight spaces. Use a conduit bender or wire bending tool designed for the purpose. This will help prevent kinking or damaging the wire. When bending, maintain a smooth, consistent radius. Avoid sharp bends that can damage the insulation.5.

Wire Lubricant

Always use a wire pulling lubricant approved for electrical use when pulling conductors through conduit, especially on long runs or with multiple bends. This significantly reduces friction and the risk of damage to the insulation.

Important Code Considerations and Safety



NEC Compliance

This is critical. Your installation must comply with the National Electrical Code (NEC) and any local amendments. The inspector is looking for safety and adherence to these standards.

Grounding

Ensure the conduit and any metal boxes are properly grounded according to the NEC.


Conduit Fill

Calculate the conduit fill to ensure that the number and size of conductors do not exceed the maximum allowed for the conduit size.

Burial Depth

Make sure the 18" burial depth meets your local code requirements.


GFCI Protection

The Tesla wall connector circuit must be GFCI protected according to the NEC. Ensure the breaker providing power to the circuit is a GFCI breaker.*

Permits and Inspections

Don't skip this step. Work with your local inspection authority and verify what is required.

Regarding Your Electrician's Price

While you may be able to do the work yourself, remember that a licensed electrician has the training, experience, and insurance to handle electrical work safely and according to code. Their pricing reflects these factors. If you are not familiar with electrical work, it's always best to consult with a qualified professional. Getting multiple quotes is always a good idea, however.

Recommendation


Review the NEC

Read the relevant sections of the NEC regarding conduit fill, bending radius, pull box requirements, and grounding. This will help you understand the requirements and ensure your installation is compliant.2.

Consider Consulting an Electrician

Even if you do the work yourself, it might be worth consulting with a licensed electrician for a short period to review your plan and ensure it meets code. This could save you time and money in the long run by avoiding costly mistakes.3.

Prioritize Safety

Electricity is dangerous. If you are not comfortable working with electricity, do not attempt this project. Hire a qualified electrician.4.

Clarify with the Inspector:
It's always a good idea to discuss your proposed solution with the inspector before you start the work. This can help you avoid further issues and ensure that your installation will pass inspection.By carefully planning your installation, using proper materials and techniques, and adhering to the NEC, you can successfully install your Tesla wall connector safely and legally. Good luck! Flag for review

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